Give classes a version number and refuse to touch classes which are not

understood.  This makes room for additional binary compatibility in the
future.

Put fields in the class for the geom's methods and initialize the methods
of a new geom from these fields.  This saves some code in all classes.

2 files changed, 27 insertions, 0 deletions

diff --git a/sys/geom/geom.h b/sys/geom/geom.h
index 82ce8fe..015baea 100644
--- a/sys/geom/geom.h
+++ b/sys/geom/geom.h
@@ -87,6 +87,7 @@ typedef void g_dumpconf_t (struct sbuf *, const char *indent, struct g_geom *,
  */
 struct g_class {
 	const char		*name;
+	u_int			version;
 	g_taste_t		*taste;
 	g_config_t		*config;
 	g_ctl_req_t		*ctlreq;
@@ -94,12 +95,24 @@ struct g_class {
 	g_fini_t		*fini;
 	g_ctl_destroy_geom_t	*destroy_geom;
 	/*
+	 * Defaults values for geom methods
+	 */
+	g_start_t		*start;
+	g_spoiled_t		*spoiled;
+	g_dumpconf_t		*dumpconf;
+	g_access_t		*access;
+	g_orphan_t		*orphan;
+	g_ioctl_t		*ioctl;
+	/*
 	 * The remaining elements are private
 	 */
 	LIST_ENTRY(g_class)	class;
 	LIST_HEAD(,g_geom)	geom;
 };
 
+#define G_VERSION_00	0x19950323
+#define G_VERSION	G_VERSION_00
+
 /*
  * The g_geom is an instance of a g_class.
  */
diff --git a/sys/geom/geom_subr.c b/sys/geom/geom_subr.c
index 2e95769..c7058ea 100644
--- a/sys/geom/geom_subr.c
+++ b/sys/geom/geom_subr.c
@@ -177,7 +177,14 @@ g_modevent(module_t mod, int type, void *data)
 	struct g_hh00 *hh;
 	int error;
 	static int g_ignition;
+	struct g_class *mp;
 
+	mp = data;
+	if (mp->version != G_VERSION) {
+		printf("GEOM class %s has Wrong version %x\n",
+		    mp->name, mp->version);
+		return (EINVAL);
+	}
 	if (!g_ignition) {
 		g_ignition++;
 		g_init();
@@ -234,6 +241,13 @@ g_new_geomf(struct g_class *mp, const char *fmt, ...)
 	TAILQ_INSERT_HEAD(&geoms, gp, geoms);
 	strcpy(gp->name, sbuf_data(sb));
 	sbuf_delete(sb);
+	/* Fill in defaults from class */
+	gp->start = mp->start;
+	gp->spoiled = mp->spoiled;
+	gp->dumpconf = mp->dumpconf;
+	gp->access = mp->access;
+	gp->orphan = mp->orphan;
+	gp->ioctl = mp->ioctl;
 	return (gp);
 }